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November 2014

Hello Analytica Users,

The November newsletter includes a wrap up of the INFORMS annual meeting (congratulations to Max on his award), some tips on mastering Time and Space and a study of the effects of bike-share programs. As always please feel free to add your questions and comments.

Paul Sanford, Newsletter Editor


Lumina project wins Decision Analysis Practice Award

We're proud to announce that a project presented by Lumina CEO, Max Henrion, won the 2014 Decision Analysis Practice Award at the 2014 INFORMS Meeting in San Francisco. The presentation "A multi-attribute decision analysis for decommissioning California’s offshore oil platforms" was coauthored with Brock Bernstein and Surya Swamy. The Award recognizes outstanding applications of decision analysis to significant decisions; it considers the quality of the analysis, its impact on the decision, and the importance and benefit of that decision. It is based on evaluations by the judges and audience. It is jointly sponsored by the Decision Analysis Society and the Society of Decision ProfessionalsWhen the project started, there was a major public controversy about what to do with oil platforms at the end of their productive life. The project team developed an Analytica model to enable stakeholders to explore and evaluate options. Eventually, stakeholders, including oil companies, environmentalists, and government agencies, reached near consensus on a "rigs to reefs" policy option. California law-makers almost unanimously passed enabling legislation, signed into law by Governor Schwarzenegger. 
For project details and model.


TIPS & TRICKS: The God Operator [ ]

Every Analytica user is familiar with the Subscript Operator (square brackets) but it's easy to overlook its true power and versatility. Often when I explain a new way to use the operator, users tell me they wish they had discovered it sooner. Square brackets can do a lot more than just single out a slice from an array. You can use them to filter, reorder, shift, re-index, re-dimension, and join data.

Imagine a one-dimensional array of data indexed by month. The subscript operator can single out a month by a specific index value: 
monthly_data[Month = 'July'] 
You could also choose the same value by specifying its position in the index using the positional operator (@):
monthly_data[@Month = 7]

That's too simple. I thought a "God Operator" would be more, you know, powerful.
OK so much for the simple subscripting review. Now here's the reason the Subscript Operator is so powerful: The right side argument inside the brackets does not have to be a single value. It can itself be another index or even a multidimensional array! Once you understand this you can make the transition from novice user to Master of Mortals and all of that. For example, suppose you're starting with a one-dimensional array containing a data value for every second in a one-hour period. It's indexed by sequential numbers from 1 to 3600. The Subscript Operator can easily convert this to a two-dimensional array by minutes and seconds. A simple expression defines the mapping:
VAR map := (Minutes_60 - 1) * 60 + Seconds_60;
New_Array:= Original_Array[Seconds_3600 = map]

This simple example partially demonstrates the power of the Subscript Operator. See Subscript and Slice operator, in the Analytica wiki to gain total mastery of how to reindex, reverse, shift, filter, sort and otherwise rearrange arrays. Please use your power wisely.


Case Study: Is Bike Sharing Good for Your Health?

With the popularity of the Healthy Cities movement, many cities are setting up bicycle rental programs not only to reduce traffic and pollution, but also to encourage physical exercise. However, riding bicycles can have higher risks of injury and exposure to pollutants than other methods of travel. Researchers used Analytica to model the effects of bike sharing programs in London and in Barcelona to find out whether these programs actually have net positive effects on health. Registration and usage data from bike-share users in both cities, survey data, and city data on travel, physical activity, traffic accidents, and air pollution were used to estimate the effect on mortality rates. For more

 

 


 

In this Issue

Lumina project wins Decision Analysis Practice Award

The God Operator [ ]

Case Study: Is Bike Sharing Good for your Health?


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Lumina is committed to continuing research and development to bring innovative decision technologies to individuals and organizations.

Lumina Decision Systems, Inc., was founded in 1991 by Max Henrion and Brian Arnold. In order to meet the needs of demanding projects, Lumina often assembles virtual organizations bringing in complementary expertise and resources from affiliated organizations, small and large. 

Its main office and R&D labs are located in Los Gatos in California's Silicon Valley.

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